Many Deep Throat theorists have guessed that Deep Throat was an FBI or White House official, but it is possible that a CIA official would have had access to the same information. In his 1994 book, "Wedge: The Secret War Between the FBI and the CIA," author Mark Riebling suggests two prime suspects from the agency's ranks.

Cord MeyerMeyer joined the CIA in 1951 at the behest of Allen Dulles, director of central intelligence, after a stint as president of the U.N.-centric United World Federalists, a post which got him denounced by Moscow Radio as "the fig leaf of American imperialism" and accused of Communist activity by Wisconsin Sen. Joseph McCarthy. At the CIA, Meyer adopted a strident anti-Soviet stance and became a top aide to Richard Helms, director of central intelligence under presidents Johnson and Nixon. Helms was fired from his post in 1973 after he refused to help Nixon use the CIA to stall the FBI's Watergate probe.

According to Riebling, Meyer fits the Deep Throat profile that Bob Woodward has sketched: intellectual, combat veteran, heavy drinker and chain smoker. Like Woodward, Meyer attended Yale. He described his experiences in a 1983 book, "Facing Reality: From World Federalism to the CIA."

Meyer also personifies the uniquely Washington phenomenon of the intermingling of government and the press. Meyer's wife, Mary Pinchot Meyer, was the sister of Washington Post executive editor Ben Bradlee's second wife, Tony Pinchot Bradlee. Meyer was estranged from his wife at the time of her murder on the towpath along the C&O Canal in Georgetown in 1964. The case has never been solved.

William E. ColbyRemembered as one of the last great "gentleman spies," Colby served as CIA director from 1973 to 1976. During Colby's tenure, the agency supported opponents of Chilean President Salvador Allende, a Marxist, who was killed during a 1973 military coup. While CIA station chief in Vietnam during the 1960s, Colby had directed Operation Phoenix, pooling U.S. intelligence resources to identify and "neutralize" Viet Cong leaders, ultimately resulting in as many as 20,000 deaths.

Colby is perhaps best known for telling Congress about the CIA "family jewels" -- detailed accounts of extensive covert operations that in 1975 prompted Sen. Frank Church (D-Idaho) to compare the agency to "a rogue elephant on the rampage." After leaving the CIA, Colby practiced law at Reid & Priest in Washington, D.C., and later at Donovan, Leisure, Newton & Irvine in Los Angeles. He also had a consulting business and spoke on the lecture circuit. In 1994 Colby signed on with Activision, an entertainment and video game publisher, to develop spy thriller video games.

Riebling counts Colby as a suspect because one of his given roles while working for Helms at the CIA was to protect the agency's image and thus to prevent it from being tarnished by the Nixon administration's troubles. According to Riebling, Woodward first met with Deep Throat within hours of Colby's damage-control assignment, and Colby was also "rumored to use underground parking structures for secret meetings."

Colby became the subject of a different mystery in April 1996 when he disappeared while canoeing on the Potomac River. He was missing for nine days before his body was found in a tributary. An autopsy revealed that Colby, age 76, had possibly suffered a stroke or heart attack before falling into the water and drowning.

The prospects that William E. Colby was Deep Throat dim considerably in light of Woodward's assertion that he would reveal Deep Throat's identity upon his death. Colby's widow, Sally Shelton-Colby, a top official at the U.S. Agency for International Development, characterized the idea of her husband as the secret Watergate source as "preposterous." "My husband wasn't Deep Throat," she said. "Bill just didn't have it in him."